Kotlin Tutorial
Null Safety in Kotlin (Explained With Examples)
Table of Contents
- Introduction
- What is Null Safety in Kotlin?
- Causes of Null Pointer Exception
- Nullable and Non-Nullable Types in Kotlin
- Kotlin Null Safety Operator
- Kotlin Program to Using Safe Operator
- Not Null Assertion !! Operator
- Gson Kotlin Null Safety
- Kotlin Full Course Video for Beginners [FREE]
Kotlin Full Course Video for Beginners [FREE]
FAQs Related to Kotlin Null Safety
A non-nullable type represents a variable that cannot hold null values, while a nullable type allows variables to hold either a non-null value of the specified type or a null value. Non-nullable types are declared without a ?, while nullable types have a ? after the type name.
You can declare a nullable variable by adding a ? after the type. For example, val name: String? = null declares a nullable string variable.
You can handle null values in Kotlin using null safety operators like ?., ?:, !!, as?, and functions like let. These operators help you safely access and manipulate nullable variables while avoiding null pointer exceptions.
The Elvis operator (?:) is used to provide a default value when an expression is null. For example, val result = nullableValue ?: defaultValue assigns defaultValue to result if nullableValue is null.
The safe call operator is used to safely access properties and methods of nullable objects. If the object is null, the expression evaluates to null instead of causing a null pointer exception.
You should use !! when you are absolutely certain that a nullable variable is not null. It asserts the non-null status of the variable. However, use it sparingly, as it can lead to a NullPointerException if misused.
Kotlin's type inference is smart enough to determine if a variable can be non-nullable or nullable based on how it's used. For example, it may infer a variable as non-nullable if you check for null explicitly or use the safe call operator.
Always prefer using safe null safety operators like ?. and ?: over the not-null assertion operator !!. Use nullable types for variables that can legitimately be null and handle null values explicitly.
The let function is used to perform an operation on a nullable object if it's not null. It's often used for transformations and applying functions to non-null objects.
